1. Field of the Invention
The present invention relates to an apparatus for making grooved filters and more particularly relates to an apparatus for making grooves in a cigarette filter. Even more particularly the present invention relates to an apparatus for making grooves in filters for cigarettes utilizing pressure and heat means for making the grooves.
2. Description of the Prior Art
In the manufacture of cigarettes, most cigarettes are provided with filter devices on the end thereof to remove undesirable materials in the smoke stream coming from the tobacco column during smoking. These filters, which are attached to the tobacco column, come in many different sizes, shapes and forms. Some filters which are presently on the market include grooves therein which facilitate in the by-passing of the smoke around the filter; provide means for mixing of the by-passed smoke stream with ventilating air; or provide means for allowing only ventilating air to pass along the groove. In the preparation of these filters, many different suggestions have been made as means for making the grooves therein. U.S. Pat. No. 3,804,695 teaches the use of a pair of parallel rolls in pressure engagement defining a nip therebetween wherein one of the rolls is provided with a circumferential or a helical grooved surface so that, as filter tow passes therethrough, permanent depressions are made along the longitudinal dimensions of the tow. U.S. Pat. No. 4,149,546 teaches an apparatus for making grooves in a cigarette filter wherein a filter rod is moved in an arcuate path transverse to a heated forming means, the filter rod being supported and conveyed for the relative movement at the periphery of a drum-shaped inner rotor and the forming means comprises a heated arcuate outer stator element or elements projecting inwardly toward the rotor.